But when Pharaoh saw. Hence it appears that the wretched tyrant, like a winding serpent, twisted and turned his mind to crooked counsels; for when he was trembling beneath the present feeling of God's power, he dared not obstinately resist any longer; he only sought a little breathing time; now, being freed from fear, he returns to his former contumacy. But this is a sign of a perverse and crooked disposition, not to submit willingly, but to pay only a temporary deference, when necessity is more than usually urgent. God foreknew, and had foretold to Moses, that this perfidy was hidden in the recesses of his heart; but he was willing to bring it to light, and therefore remitted the punishment; and hence was the opportunity for dissembling.

But when Pharaoh saw that there was respite,.... From his affliction, as the Targum of Jonathan adds; the plague was removed, and he found himself and his people at ease: or there was a "breathing" (c); before he and his people were so oppressed, that they could scarce breathe, but now being delivered from the judgment on them with which they were straitened, were enlarged and at liberty, and in easy circumstances: he hardened his heart; See Gill on Exodus 7:14.
and hearkened not unto them; to Moses and Aaron, to let the children of Israel go, as they had required, and he had promised:
as the Lord had said; had foretold that he would not hearken to them, nor let Israel go as yet.
(c) "respiratio", Pagninus, Montanus, Tigurine version, Junius and Tremellius, Piscator, Drusius.

But when Pharaoh saw that there was respite, he hardened his heart - Observe he did it himself, not God, any otherwise than by not hindering.